Flat multifilament yarn knitted fabric

ABSTRACT

A flat multifilament yarn knitted fabric having excellent bulkiness, drape, and water·sweat-absorbability is a knitted fabric comprising multifilament yarns each comprising a plurality of flat cross section shape-having filaments comprising a fiber-forming thermoplastic polymer as a main component. In the above-described flat cross section, three or more expanded portions expanded toward the outside of the longitudinal central line of the flat cross section per half side of the flat cross section, and two or more constricted portions formed between the expanded portions per half side are approximately symmetrically formed on both the sides of the longitudinal central line with respect to the above-described longitudinal central line. Cross section flatness represented by the ratio (B/C1) of the length (B) of the above-described modified cross section in the direction of the longitudinal central line to the maximum width (C1) in the direction orthogonal to the direction of the longitudinal central line is in a range of 2 to 6. The above-described multifilament yarns are comprised in the knitted fabric in an amount of 50 to 100 percent by weight based on the total weight of the knitted fabric.

TECHNICAL FIELD

[0001] The present invention relates to a flat multifilament yarnknitted fabric. In more detail, the present invention relates to aknitted fabric which comprises multifilament yarns comprising flat andtwo or more constricted portion-having filaments and has bulkiness,excellent drape and high water absorbability.

BACKGROUND ART

[0002] Hitherto, many knitted fabrics have been proposed in the fieldsof inner wears represented by underwear, sports wears, and the like.Since the knitted fabrics for the inner wears among them are directlybrought into contact with the skins, excellent drape, bulkiness andwater absorbability are required.

[0003] On the other hand, fibers comprising a fiber-formingthermoplastic polymer such as a polyester or a polyamide have been usedin a wide range from clothing uses to industrial uses due to theexcellent characteristics of the fibers. Polyester fibers among thefibers have widely been used as yarns constituting woven fabrics,because of having many excellent characteristics such as excellent fiberstrengths, dimensional stability and easy care property.

[0004] However, there has been a problem that the drape of a knittedfabric has been deteriorated, when yarns comprising a fiber-formingthermoplastic polymer are subjected to a false-twisting and crimpingtreatment and then knitted into the knitted fabric to enhance itsbulkiness.

[0005] Such the drape and the bulkiness are generally the mutuallyconflicting properties. For example, there has been a problem that thebulkiness of a knitted fabric has been deteriorated, when the knittedfabric is subjected to an alkali reduction treatment to enhance thedrape of the knitted fabric or when twisted yarns are knitted into theknitted fabric to enhance its drape.

[0006] Additionally, the water absorbability of a knitted fabric formedfrom yarns comprising a fiber-forming thermoplastic polymer- is usuallyinsufficient. The improvement of the water absorbability has thereforebeen required.

[0007] As a knitted fabric having the water absorbability and the drape,a knitted fabric comprising multifilament yarns each comprising aplurality of flat W-shaped cross section shape-having filaments has beenproposed in JP-A 11-222721 (hereinafter, JP-A means “Japanese UnexaminedPatent Publication”).

[0008] However, such the knitted fabric comprising the multifilamentyarns each comprising a plurality of the flat W-shaped cross sectionshape-having filaments has excellent water absorbability, but is stillinsufficient at the point of the drape.

DISCLOSURE OF INVENTION

[0009] The object of the present invention is to provide a knittedfabric having bulkiness, excellent drape and high water absorbability.The above-described object can be achieved with the flat multifilamentyarn knitted fabric of the present invention.

[0010] The flat multifilament yarn knitted fabric of the presentinvention is a knitted fabric comprising multifilament yarns eachcomprising a plurality of flat cross section shape-having filamentscomprising a fiber-forming thermoplastic polymer as a main component,characterized in that

[0011] three or more expanded portions expanded toward the outside ofthe longitudinal central line of the flat cross section of theabove-described filament per half side of the flat cross section and twoor more constricted portions formed between the expanded portions perhalf side are formed on both the sides of the longitudinal central line,approximately symmetrically with respect to the above-describedlongitudinal central line, in the flat cross section of the filament;

[0012] cross section flatness represented by the ratio (B/C1) of thelength (B) of the above-described modified cross section in thedirection of the longitudinal central line to the maximum width (C1) inthe direction orthogonal to the direction of the longitudinal centralline is in a range of 2 to 6;

[0013] and

[0014] the above-described multifilament yarns are comprised in theknitted fabric in an amount of 50 to 100 percent by weight based on thetotal weight of the knitted fabric.

[0015] Therein, the above-described fiber-forming thermoplastic polymeris preferably selected from polyesters, polyamides, polyvinylidenechloride, and polypropylene.

[0016] Further, in the flat cross section of the above-describedfilament, it is preferable that the ratio (C1/C2) of the maximum width(C1) to the minimum width (C2) is 1.05 to 4.00.

[0017] It is preferable that the above-described multifilament yarnscontains a matting agent in an amount of not less than 0.2 percent byweight, because more excellent drape is obtained. The total fineness ofsuch the multifilament yarn is preferably 20 to 170 dtex, and thefineness of the single filament is preferably 0.5 to 5 dtex.

[0018] In the flat multifilament yarn knitted fabric of the presentinvention, it is preferable that the knit construction is a knitconstruction selected from ponti roma, Milano rib, tuck rib, back seedstitch (back Kanoko), single pique, double pique, half, satin, backhalf, queens cord, shark skin, double raschel, and double tricot.

[0019] In the flat multifilament yarn knitted fabric of the presentinvention, it is preferable that a K value determined by the followingexpression is not more than 35×10³, as the whole of the knitted fabric.When such the K value is more than 35×10³, the bulkiness is liable to isdeteriorated.

K=Co×We×(D/1.1)^(1/2)

[0020] wherein Co is the courses (courses/2.54 cm) of the knittedfabric; We is the wales (wales/2.54 cm) of the knitted fabric; D is theaverage value (dtex) of the total finenesses of the yarn constitutingthe knitted fabric.

[0021] In the flat multifilament yarn knitted fabric of the invention,it is preferable that the bulkiness of the knitted fabric, measured byJIS L 1018-1998, 6. 20, is not less than 2.1 cm³/g. Further, it ispreferable that the flexural rigidity of the knitted fabric, measured bya KES hand-measuring system, is not more than 0.02 cN·cm²/cm.Furthermore, it is preferable that the water-absorbing speed of theknitted fabric, measured by JIS L 1096-1998, 6. 26, 1(2) B method(Byreck method), is not less than 30 mm.

BRIEF DESCRIPTION OF DRAWINGS

[0022]FIG. 1 is an explanatory drawing showing an example of the crosssection shape of each of the filaments constituting the flatmultifilament yarns comprised in the flat multifilament yarn knittedfabric of the present invention.

[0023]FIG. 2 is an explanatory drawing showing the other example of thecross section shape of each of the filaments constituting the flatmultifilament yarns comprised in the flat multifilament yarn knittedfabric of the present invention.

[0024]FIG. 3 is an explanatory drawing showing the further other exampleof the cross section shape of each of the filaments constituting theflat multifilament yarns comprised in the flat multifilament yarnknitted fabric of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0025] The inventors of the present invention have found the following.In a knitted fabric comprising multifilament yarns each comprising aplurality of flat cross section shape-having filaments comprising afiber-forming thermoplastic polymer as a main component, wherein threeor more, preferably four or more, further preferably four to six,expanded portions expanded toward the outside of the longitudinalcentral line of the flat cross section of the above-described filamentper half side of the flat cross section and two or more, preferablythree or more, further preferably three to five, constricted portionsformed between the expanded portions per half side are formed on boththe sides of the longitudinal central line, approximately symmetricallywith respect to the above-described longitudinal central line, in theflat cross section of the filament, and further wherein cross sectionflatness represented by the ratio (B/C1) of the length (B) of theabove-described modified cross section in the direction of thelongitudinal central line to the maximum width (C1) in the directionorthogonal to the direction of the longitudinal central line iscontrolled within a range of 2 to 6, excellent bulkiness is obtained,because the flat multifilament yarns are tightly brought into contactwith each other on their flat surfaces at the connection points of theknitted fabric construction due to the contact pressure of theconstruction and simultaneously slipped and spread to form the loops ofthe knitted fabric, and high flexibility at the connection points of theknitted fabric construction and excellent drape are also obtained,because the surfaces of the mutually overlapped flat filaments areroughed with the expanded portions and the constricted portions toreduce frictional resistance between the filaments.

[0026] Further, the inventors of the present invention have found thatthe constricted portions formed on the flat surfaces of the flatmultifilament yarns develop capillary phenomena for liquids, whereby theknitted fabric of the present invention exhibits excellent waterabsorbability and excellent sweat absorbability for water and sweat,respectively.

[0027] The present invention has been completed on the basis of theabove-described findings.

[0028] The flat multifilament yarn knitted fabric of the presentinvention is the knitted fabric comprising the multifilament yarns eachcomprising a plurality of the flat cross section shape-having filamentscomprising the fiber-forming thermoplastic polymer as the maincomponent.

[0029] In the above-described multifilament yarn, the cross sectionshape of the single filament is a shape in which the width in thedirection vertical to the longitudinal central line is relativelyshorter than the length of the central line, namely a flat shape, forexample, as shown in FIG. 1.

[0030] In the cross section 1 shown in FIG. 1, three or more (four inthe FIG. 1) expanded portions 3 expanded toward the outside of thelongitudinal central line 2 per half side of the cross section and twoor more (three in FIG. 1) constricted portions formed between theexpanded portions 3 per half side are formed on both the sides of thelongitudinal central line, symmetrically with respect to thelongitudinal central line.

[0031] Herein, the expanded portions formed on one side areapproximately symmetrically placed to the expanded portions formed onthe other side with respect to the longitudinal central line, and theconstricted portions formed on one side are also approximatelysymmetrically placed to the constricted portions formed on the otherside with respect to the longitudinal central line. But it is notnecessary that the shapes of the expanded portions and the constrictedportions formed on both the sides are perfectly symmetrical.

[0032] In the cross section of FIG. 1, the cross section flatnessrepresented by the ratio (B/C1) of the maximum length (B) in thelongitudinal direction to the maximum width (C1) in the directionorthogonal to the longitudinal direction is in a range of 2 to 6.

[0033] In the cross section of the single filament in theabove-described flat multifilament yarn, the number of the expandedportions is three or more, preferably four or more, further preferablyfour to six, per one side, as described above. The number of theconstricted portions is also two or more, preferably three or more,further preferably three to five, per one side, as described above.Additionally, the cross section flatness is 2 to 6, preferably 3 to 5,as described above.

[0034] When the number of the expanded portions is two or less, thereby,when the number of the constricted portion is one or less per one side,frictional resistance on the peripheral surface of the filament isenlarged, and the spreading of the knitted fabric construction due tothe pressure contact at the connection points is insufficient. Thewater·sweat absorbability of the obtained knitted fabric is alsoinsufficient, because the constricted portions on the peripheral surfaceof the filament are reduced.

[0035] In the flat multifilament yarn knitted fabric of the presentinvention, the cross section flatness (B/C1) in the cross section of thesingle filament in the flat multifilament yarn is 2 to 6, preferably 3to 5, as described above. When the cross section flatness is less than2, the flexural rigidity of the filament is enhanced, and the desireddrape is therefore not obtained. Further, when the cross sectionflatness is less than 2, the spreading of the multifilament yarns due tothe pressure contact in the knitted fabric, especially at the connectionpoints of the knitted fabric construction, is insufficient, and thedesired drape is therefore not obtained.

[0036] In the cross section shape of the single filament in the flatmultifilament yarn used in the knitted fabric of the present invention,the ratio (C1/C2) of the maximum width (C1) in the direction orthogonalto the longitudinal central line to the minimum value (C2) is preferably1.05 to 4.00, more preferably 1.10 to 2.50. The above-described ratio(C1/C2) is a parameter related to the depth of the constricted portionof the single flat filament. When the ratio (C1/C2) is less than 1.05,namely when the depth of the constricted portion is small, frictionalresistance between the filaments is enlarged. Thereby, flexibility atthe connection points of the knitted fabric construction is oftendeteriorated, and the drape of the knitted fabric is therefore ofteninsufficient. Further, the water·sweat absorbability of the knittedfabric is often insufficient. When the ratio (C1/C2) exceeds 4.0, thedepth of the constricted portion is excessively enlarged, and the actioneffect is saturated. Furthermore, troubles such as the unstableness offiber productivity, the development of cracks in the constrictedportion, and the deterioration in the uniformity of the filament crosssection are often caused.

[0037] The other examples of the cross section shape of the singlefilament in the flat multifilament yarn used in the flat multifilamentyarn woven of the present invention are shown in FIGS. 2 and 3,respectively.

[0038] The cross section of the filament 1 shown in FIG. 2 has the sameshape as the cross section shape described in FIG. 1 on both the sidesof the longitudinal central line 2, but the cross section shape of theexpanded portion 3 is gentle like an arc along the major axis of anellipse. Thereby, the depth of the constricted portion 4 is small.

[0039] The cross section of the filament 1 shown in FIG. 3 has fourexpanded portions and three constricted portions per one side on boththe sides of the longitudinal central line, but the width and height ofone expanded portion 3 a are smaller than those of the other expandedportions. Thereby, the depths of the valley bottoms of the constrictedportions 4 a on both the sides from the tips of the expanded portion 3 aare smaller than those of the other constricted portion 4.

[0040] Next, the filaments constituting the multifilament yarns comprisethe fiber-forming thermoplastic polymer. Said fiber-formingthermoplastic polymer is especially not limited, and includes polyestersrepresented by polyethylene terephthalate and polytrimethyleneterephthalate, polyamides, polyvinylidene chloride, polypropylene, andtheir copolymers copolymerized with the third components. Among them,the polyesters are preferably exemplified, because of being easilyproduced.

[0041] And, it is preferable on the acquisition of more excellent drapethat said fiber-forming thermoplastic polymer contains a matting agentin an amount of not less than 0.2 percent by weight (more preferably 1.0to 3.5 percent by weight, especially preferably 1.5 to 2.8 percent byweight). Such the matting agent includes known inorganic fine particlessuch as titanium dioxide.

[0042] Except the matting agent, the above-described fiber-formingthermoplastic polymer may, if necessary, furthermore contain one or moreadditives selected from fine pore-forming agents (for example, metalorganic sulfonates), cation dye-dyeable agents (for example, isophthalicacid sulfonium salts), antioxidizing agents (for example, hinderedphenol-based antioxidizing agents), heat stabilizers, flame retardants(for example, antimony trioxide), fluorescent brightening agents,colorants, antistatic agents (for example, metal sulfonates), moistureabsorbents (for example, polyoxyalkylene glycols), and the like.

[0043] The total fineness of said multifilament yarn and the fineness ofsaid single filament are especially not limited, but it is preferable onthe acquisition of bulkiness, excellent drape and high waterabsorbability that the total fineness of the multifilament yarn and thefineness of the single filament are 20 to 170 dtex (more preferably 30to 100 dtex) and 0.5 to 5 dtex (more preferably 1 to 4 dtex),respectively.

[0044] In the flat multifilament yarn used the flat multifilament yarnknitted fabric of the present invention, the twist rate of the yarn isespecially not limited, can suitably be set, but is generally preferably0 to 2,500 T/m, more preferably 0 to 600 T/m, especially preferably 0T/m (untwisted), on the acquisition of excellent drape.

[0045] The multifilament yarn used in the present invention may besubjected to a twisting treatment such as a false twisting treatment orto an air treatment such as Taslan treatment or an interlacingtreatment, so long as the objective knitted fabric of the presentinvention is obtained.

[0046] It is necessary that such the multifilament yarns are containedin an amount of 50 to 100 percent by weight, preferably 60 to 100percent by weight, especially preferably 100 percent by weight, based onthe total amount of the knitted fabric. The smaller content of saidmultifilament yarns than 50 percent by weight is not preferable, becausesufficient bulkiness, drape and sweat absorbability are not obtained.When the content of the multifilament yarns is not less than 50 percentby weight, the flat multifilament yarn knitted fabric of the presentinvention may be interknitted with a different kind of yarns. Theabove-described different kind of yarns include monofilament yarns,multifilament yarns and spun yarns, and may have one or more specialfunctions such as an antistatic function and a brightening function.Further, the flat multifilament yarns may singly constitute the knittedfabric or constitute the knitted fabric together with a different kindof yarns in the form of composite yarns such as twisted yarns or airblended yarns.

[0047] In the flat multiflament yarn knitted fabric of the presentinvention, the density of the knitted fabric is especially not limited,but the ranges of 40 to 80 courses/2.54 cm (more preferably 50 to 70courses/2 54 cm) and 30 to 70 wales/2.54 cm (more preferably 40 to 65wales/2.54 cm) are suitable for satisfying both the performances ofdrape and bulkiness.

[0048] Especially, it is preferable that a coefficient K determined bythe following expression is not more than 35×10³ (preferably 17×10³ to30×10³, especially preferably 20×10³ to 28×10³).

K=Co×We×(D/1.1)^(1/2)

[0049] wherein Co is the courses (courses/2.54 cm) of the knittedfabric; We is the wales (wales/2.54 cm) of the knitted fabric; D is theaverage value (dtex) of the total finenesses of the yarn constitutingthe knitted fabric.

[0050] When the above-described K value is larger than 35×10³, the Kvalue is not preferable, because sufficient bulkiness is not obtained.When said K value is conversely less than 17×10³, sweat absorption maybe deteriorated.

[0051] In the flat multifilament yarn knitted fabric of the presentinvention, the knit construction is especially not limited, and a knownknit construction such as a warp knit construction or a circular knitconstruction can be used. For example, circular knitted fabrics such asponti roma, Milano rib, tuck rib, back seed stitch (back Kanoko), singlepique and double pique, single warp knitted fabrics such as half, satin,back half, queens cord and shark skin, and double warp knitted fabricssuch as double raschel, and double tricot are cited.

[0052] The flat multifilament yarn knitted fabric of the presentinvention can be produced, for example, by spinning with a spinnerethaving such the shape nozzles as shown in FIG. 2C at page 5 in JP-A56-107044 to obtain the flat multifilament yarn, if necessary, combiningthe obtained flat multifilament yarn with a different kind of yarn toform the composite yarn, and then knitting the composite yarn by anordinary knitting method. The knitted fabric of the present inventioncan be dyed and finished by ordinary methods. When the flatmultifilament yarn is a polyester yarn, an alkali reduction treatmentcan be applied to said knitted fabric. In the finishing treatment, oneor more of a water absorbability-promoting treatment (for example, atreatment for coating or impregnating a water-absorbing agent such as ananionic hydrophilic polymer), a water-repelling treatment (for example,a treatment for coating or impregnating a water-repelling agent such asa fluorinated compound), an ultraviolet light-screening treatment (forexample, a treatment for coating or impregnating a finely particulatemetal oxide), an antistatic treatment, a deodorizer-imparting treatment,a mothproofing agent-imparting treatment, and a luminous agent treatmentmay simultaneously or sequentially be applied.

[0053] In the flat multifilament yarn knitted fabric of the presentinvention, bulkiness measured according to JIS L 1018-1998, 6. 20 ispreferably not less than 2.1 cm³/g, especially preferably 2.2 to 3.0cm³/g.

[0054] Further, in the flat multifilament yarn knitted fabric of thepresent invention, flexural rigidity measured with a KES hand-measuringsystem as drape is preferably not more than 0.02 cN·cm²/cm, especiallypreferably 0.010 to 0.018 cN·cm²/cm.

[0055] Furthermore, in the flat multifilament yarn knitted fabric of thepresent invention, water-absorbing speed measured by JIS L 1018-1998, 6.26, 1(2) B method (Byreck method) is preferably not less than 30 mm,especially preferably 50 to 70 mm.

[0056] In the flat multifilament yarn woven fabric of the presentinvention, excellent bulkiness is obtained, because the flatmultifilament yarns constituting the knitted fabric are slipped on themutual contact surfaces of the mutually contacting single filaments withcontact pressures at the connection points of the knitted fabricconstruction, flattened, and simultaneously spread in the lateraldirection to form the loops of the knitted fabric.

[0057] Further, in the flat multifilament yarn woven fabric of thepresent invention, the knitted fabric exhibiting lowered bendingresistance, improved flexibility and excellent drape is obtained by theabove-described flattening of the yarns. Additionally, the peripheralsurface of the single filament in the flat multifilament yarn isroughened with three or more expanded portions per one side and with twoor more constricted portions formed therebetween. Even when the singlefilaments contact with each other or even when the single filaments arebrought into press contact with each other at the connection points ofthe knitted fabric construction, the contact area between the singlefilaments is small. Thereby, the surface frictional resistance isreduced to contribute to the improvement in the drape of the knittedfabric. Further, even when the single filaments contact with each other,the constricted portions on the peripheral surfaces of the singlefilaments are not or slightly closed. Therefore, water or sweat iseasily diffused by the capillary phenomena of the constricted portions,and the obtained knitted fabric exhibits excellent water absorbabilityand sweat absorb ability.

[0058] The flat multifilament yarn knitted fabric of the presentinvention is suitably used as a material for various clothes, forexample, for inner wears such as underwear and sports wears, because ofhaving the high bulkiness, excellent drape, and high water·sweatabsorbability.

EXAMPLES

[0059] The present invention will be explained in more detail hereafterwith the following examples, but the present invention is not limited tothe examples. Therein, measurement items in Examples were measured bythe following methods, respectively.

[0060] (1). Water Absorbability

[0061] The water absorbability was measured by JIS L 1096-1998, 6. 26,1(2) B method with the number n of 5, and the average value wascalculated.

[0062] (2). Bulkiness

[0063] The bulkiness was measured by JIS L 1018-1998, 6. 20 with thenumber n of 5, and the average value was calculated.

[0064] (3). Flexural Rigidity

[0065] The flexural rigidity was measured with KES (Kawabata EvaluationSystem) hand-measuring system (type KESFB2, manufactured by Kato TechCo.) with the number n of 5, and the average value was calculated.

[0066] (4). Hand

[0067] The hand was classified into the following five grades with handtouch and evaluated.

[0068] 5 grade: extremely high flexibility, extremely excellent hand.

[0069] 4 grade: high flexibility, excellent hand.

[0070] 3 grade: good flexibility, good hand.

[0071] 2 grade: slightly insufficient flexibility, slightlydissatisfactory hand.

[0072] 1 grade: bad flexibility, bad hand.

[0073] (5). Over-all Evaluation

[0074] The over-all evaluation was classified into the following fourgrades.

[0075] 4 grade: extremely excellent.

[0076] 3 grade: excellent.

[0077] 2 grade: slightly dissatisfactory.

[0078] 1 grade: bad.

Example 1

[0079] Polyethylene terephthalate resin containing titanium dioxide inan amount of 2.5 percent by weight as a matting agent was extruded at aspinning temperature of 300° C. through thirty melt-spinning holes (eachhole has four circular expanded portions and three constricted portionsformed between the expanded portions per one side on both the sides ofthe longitudinal central line) opened in a spinneret and each having ashape corresponding to the filament cross section shape shown in FIG. 1.The extruded filament-like melted polymer flows are cooled andsolidified and simultaneously taken off at a take-off speed of 4,000m/min. The obtained undrawn multifilaments were not wound up andimmediately drawn at a draw ratio of 1.3 at a temperature of 97° C. toproduce the drawn multifilament yarn having a yarn count of 84 dtex/30filaments. This drawn multifilament yarn comprised the filaments eachhaving the cross section shape shown in FIG. 1. The cross sectionflatness of the cross section shape of each filament was 3.2, and aratio C1/C2 value in the cross section width of the filament was 1.2.

[0080] Subsequently, said flat multifilament yarns thus produced werefed into a front reed and a back reed in an untwisted state, and thenknitted by an ordinary knitting method (tricot knitting machine, 28G) toobtain the knitted fabric containing 100% of the above-described flatmultifilament yarns and having a half knit construction (back: 12/10,front: 10/23). The knitted fabric was subjected to ordinary dyeing andfinishing treatments. The finished knitted fabric had a knit density (62courses/2.54 cm, 50 wales/2.54 cm, K value 26.84×10³).

[0081] In said knitted fabric, sweat absorbability: 56 mm, bulkiness:2.27 cm³/g, flexural rigidity: 0.017 cN·cm²/cm, hand: 5 grade, over-allevaluation: 4 grade.

Example 2

[0082] A flat multifilament yarn knitted fabric was obtained similarlyto Example 1, except that the knit density was changed into a knitdensity (70 courses/2.54 cm, 50 wales/2.54 cm, K value 30×10³), whileusing the same yarns.

[0083] In said knitted fabric, sweat absorbability: 57 mm, bulkiness:2.20 cm³/g, flexural rigidity: 0.018 cN·cm²/cm, hand: 4 grade, over-allevaluation: 3 grade.

Example 3

[0084] A flat multifilament yarn knitted fabric was obtained similarlyto Example 1, except that the content of the titanium dioxide waschanged to 0.2 percent by weight.

[0085] In said knitted fabric, sweat absorbability: 56 mm, bulkiness:2.20 cm³/g, flexural rigidity: 0.018 cN·cm²/cm, hand: 5 grade, over-allevaluation: 3 grade.

Comparative Example 1

[0086] A knitted fabric was obtained similarly to Example 1, except thatthe cross section shape of the filament was changed to a circular crosssection.

[0087] In said knitted fabric, sweat absorbability: 25 mm, bulkiness:2.08 cm³/g, flexural rigidity: 0.024 cN·cm²/cm, hand: 2 grade, over-allevaluation: 1 grade.

Comparative Example 2

[0088] A knitted fabric was obtained similarly to Example 1, except thatthe knitted fabric having the same half knit construction as in Example1 was made by feeding all of the multifilament yarns used in ComparativeExample 1 into the back reed and alternately feeding four of themultifilament yarns used in Comparative Example 1 and one of the flatmultifilament yarns used in Example 1 into the front reed, so that thecontent of the flat multifilament yarns used in Example 1 and thecontent of the multifilament yarns used in Comparative Example 1 were 10percent by weight and 90 percent by weight, respectively.

[0089] In said knitted fabric, sweat absorbability: 28 mm, bulkiness:2.10 cm³/g, flexural rigidity: 0.022 cN·cm²/cm, hand: 3 grade, over-allevaluation: 2 grade.

INDUSTRIAL APPLICABILITY

[0090] The flat multifilament yarn knitted fabric of the presentinvention has excellent bulkiness and drape, because the singlefilaments well slip due to their special cross section shapes andfurther because the yarns are flattened and spread in the lateraldirection at the connection points of the knitted fabric constructionwith contact pressures to form the loops of the knitted fabric, andfurther has excellent water absorbability and sweat absorbability.Thereby, the flat multifilament yarn knitted fabric of the presentinvention is useful as a knitted fabric for inner wears such asunderwear and as a sports wear.

What is claimed is:
 1. A flat multifilament yarn knitted fabriccomprising multifilament yarns each comprising a plurality of flat crosssection shape-having filaments comprising a fiber-forming thermoplasticpolymer as a main component, characterized in that three or moreexpanded portions expanded toward the outside of the longitudinalcentral line of the flat cross section of the above-described filamentper half side of the flat cross section and two or more constrictedportions formed between the expanded portions per half side are formedon both the sides of the longitudinal central line, approximatelysymmetrically with respect to the above-described longitudinal centralline, in the flat cross section of the filament; cross section flatnessrepresented by the ratio (B/C1) of the length (B) of the above-describedmodified cross section in the direction of the longitudinal central lineto the maximum width (C1) in the direction orthogonal to the directionof the longitudinal central line is in a range of 2 to 6; and theabove-described multifilament yarns are comprised in the knitted fabricin an amount of 50 to 100 percent by weight based on the total weight ofthe knitted fabric.
 2. The flat multifilament yarn knitted fabricaccording to claim 1, wherein the above-described fiber-formingthermoplastic polymer is selected from polyesters, polyamides,polyvinylidene chloride, and polypropylene.
 3. The flat multifilamentyarn knitted fabric according to claim 1, wherein the ratio (C1/C2) ofthe maximum value (C1) of the width to the minimum value (C2) in theflat cross section of the above-described filament is 1.05 to 4.00. 4.The flat multifilament yarn knitted fabric according to claim 1, whereinthe above-described filament yarn contains a matting agent in an amountof not less than 0.2 percent by weight.
 5. The flat multifilament yarnknitted fabric according to claim 1, wherein the total fineness of theabove-described multifilament yarn is 20 to 170 dtex, and the finenessof the single filament is 0.5 to 5 dtex.
 6. The flat multifilament yarnknitted fabric according to claim 1, wherein the above-described knittedfabric has a knit construction selected from ponti roma, Milano rib,tuck rib, back seed stitch (back Kanoko), single pique, double pique,half, satin, back half, queens cord, shark skin, double raschel, anddouble tricot.
 7. The flat multifilament yarn knitted fabric accordingto claim 1, wherein a K value determined by the following expression isnot more than 35×10³, as the whole of the above-described knittedfabric. K=Co×We×(D/1.1)^(1/2) wherein Co is the course number(courses/2.54 cm) of the knitted fabric; We is the wale number(wales/2.54 cm) of the knitted fabric; D is the average value (dtex) ofthe total finenesses of the yarns constituting the knitted fabric. 8.The flat multifilament yarn knitted fabric according to claim 1, whereinthe bulkiness of the above-described knitted fabric, measured by JIS L1018-1998,
 6. 20, is not less than 2.1 cm³/g.
 9. The flat multifilamentyarn knitted fabric according to claim 1, wherein the flexural rigidityof the above-described knitted fabric, measured with a KEShand-measuring system, is not more than 0.02 cN·cm²/cm.
 10. The flatmultifilament yarn knitted fabric according to claim 1, wherein thewater-absorbing speed of the above-described knitted fabric, measured byJIS L 1096:1998,
 6. 26, 1(2) B method (Byreck method), is not less than30 mm.